Colloidizing of the mixed esters of cellulose with the alkylene halides



Patented July 2, 1935 f Y' i i?" i l inventien relates to Lthe.ce11e.i .1ining fof [the liet/@else i9kwd=thetethe-vmixed resters' lef .nele fhihe-:esters ef leellnleln; bymeenegef; elle??? llltlhseiy'elltning'leteer Whn ..e9elt,e dinte enefehlorisles,'suenan-ethylene ehleriselob (dise mine-mln" lenenmnntsielfenex nnnlnY "ibiit sem-ns theee-eetenn the @elw-.Iene enleridefand A, Stbilityeveif 5 evnnexntinefeffthe selvente f,

ithes-fnrevipnslyheen knewntnaeelledize @.64111- true With'elarge number Of plestiizeth v 4lese :acetate withlaeetenete fernnsheetsn Y. mere-@lerge-nnn1her .pf xeeaf ineen erge ,made .Grier'thatinettterfenyeelleilized-nreduet .f Meten? Solutions Qfaulhydflyzd ne we eyenwhen ist ,isntternnted te e'elleid.. HIT Pe een.- attienePeetlenensflalmes e. o .esters Awith aeetene seme ef tnesheetsftenneel MenelfPllndWfblehmull Inaintennenbilityn e L10 ene .fennd :te .be new, sszrnefneineenwfel 1y 5t C entfen'nweethene f ewfietsy `Whfnlffftts y hazy While other samples had a markehhagm tlpllefne ehlgljgife employed ytnlder Also it was lfennel that sheets ,ef --minedfesters .which differed -Qn1y-in the ,nrenentipneef-,tne J5 @steelspresent,variedte:nnalnwetznnhelieyeble extent Lin their fflexibilityg zA ,r-insteneeeenmlee fQf, nellnlese .aeetateanreniennte in tnel'eengitiens, e ,number ef statines were any en, theilattersemplea 4etlney@wereau. founder) Mchte .e have quite satisfactory f1exihi1ity.-E'.our;,-of the .f-'Hlrty'f ll hadfbeen eoatedtrom acetone, v-tolzr. ted fpldsuponfbeingtestedo Sampleskoffthe .foumgimerent cellulose 1acetateepropionates;the

ett-the end et phates. Thus it may be seen that the alkylene tive sheeting or film. The usual vfilm forwsheet exhibits a surface all points of which are not in the same plane, the amount o fcurvature of such a surface varying with the particularl sheeting. duced by coating from a solution of a mixed ester,

such as cellulose acetate-propionate in ethylene! chloride, the sheet or film produced has the property of flatness or, in other words, presentsa sur.-`

face suflicientlyplane for allf practical purposes.

AThis property :is important in 'photographicV nlm to avoid distortion of the 1im`age'of 4'the film; and

is a very unusual and usefuljproprty inthe case of organic esters of cellulose, particularly "when accompanied by good flexibilityas in the. caseof myinvention.` l It" has been known to coat 'cellulose acetate sheets, from asolution' in" whichv a" mixturel'of ethylene chloride'and a.y lower alcohol is the solvent. However, itisimpossible to employ ethylene V'chloride alone 'for this purpose, primarily dueto the poor solubility of cellulose acetate in ethylene chloride. Previous'torm'yrdiscovery, it`was notr realized that .the `alkylene chlorides, either by themselves or mixed withv the lower alcohols, were suitable for colloidizlng vva'- rious mixed estersofl cellulose, and in viewof the unsatisfactory 'experience inthe' artwith attempts to dissolvev 'cellulose' acetate in Aethylene chloride it is all theV more notable' a'discovery` that the alkylene chlorides should' `be` found'to contribute suoli new and'lunusual' properties tolcellulose mixed vand single higher organic esterI compositions. 1

`I have found thatthe zalkyle'rie chlorides, such as methylene'chloride, ethylene chloride, propylene chloride etc.,' are eminently suite'dforjtliecolloidizing of the mixed` e'sters of cellulose. f The colloidized cellulosic materials'jcoated ktherefrorn are found to. be uniform,f free f romhaze and'flexibl'e.' y y homologous `organic series;A the lwer members of the present series exhibitf greaterl solubility powers. 'Where' the' alkyleneichloride is j not a solvent for the cellulose ester,y as is sometimesthe kcase with the alkylene 'chlorides 'above ethylene v37% stearylzcontent was .dissolvedv in about 800 fparts of propylene chloride. Thesolution-was chloride, other lower boiling`"`solvents such as a lower alcohol mayjbe added, soythatfa solvent mixture for the'v cellulose ester is formed; For

example, it isfwell known'that'cellulose acetate is insoluble in propylene' chloride; and this property of insolubility in propylene chloride is also foundin some of the mixed esters in whichapetyl groups predominate a'nd,in such a'case; the addition of alcohol is'nec'essary'to promote solubility.

In cases where'the acetylgroupsaefpresent'to a less extent, however, such, for example, asl cellulose acetate-propionate of more `than V15 %y propionyl'content,the mixed esters soluble in prov'pylene chloride. The presence of higher 'fatty acid groupsjtends to promote' solubility in' propylene chloride, this 'tendency 'increasing`, of

' course, with the number of. carbon atoms' present in the radical.j L There may ,be instances where even ethylene-chloride wil-1 "notuisoive the mixed the property of ilatness is a characteristic dbf-cellulosel deriva- I have found that when sheeting is pro-.

ester of cellulose as, for instance, where it has been hydrolyzed to a point, beyond solubility in ethylene chloride, (the hydrolysis of mixed organic esters of cellulose `being described and claimed in Malm and Fletcher application Serial No. 551,546, illed July V1'7, '1931. `In `such cases a small amount of a lower 'alcohol (methyl or ethyl) may, obviously, be added to assist in disisolving the ester.

I have found that the alkylene chlorides, especially ethylene chloride, when employed as the solvent in the colloidizing of cellulose esters, eliminates anyldanger. of haze in the resulting l plduct." is believed to be due to the formagtionyby,` the 'alkylene chloride of an azeotropic boiling mixture with the moisture which may be present. Be-that asl it may, I have found that coating from an alkylene chloride solution eliminate'sI the'variations in the physical properties of lms coated under different relative humidity conditions vonfrom -clopesl containing different amounts of moisture.vv The moisture inthe dope apparently evaporates first upon colloidizing, leaving the cellulosic compound always toform the film from an anhydrous single solvent solution, which bears yout lmy vtheory 'as' to an azeovtropic mixture being present. f As is well known the presence of 4water. will cause opacity,` and vthis `danger is entirely eliminated, without the necessity of the absolute vconditions usually employed'in colloidizing'processes, such asthe coat- I have found that various mixed yesters of cellulose, both nitrogen containing and nonnitrogen containing,` may be employed.` -Obviously if desired, a mixture of mixed-esters or of a mixed ester and a simple ester such as cellulose stearate, cellulose butyrate etc. may becolloidized by my process. If desired, vknown plasticizers, such Vas for instance, the triaryl phosphates yor .plastic materials such as gums, fats, waxes, resins etc. may be incorporated, if desired,-where compatible-'with the particulary composition.

Some of the v mixed esters which preferably may be employed arezg' i Y Y 7 Cellulose acetate nitrate v u Cellulose acetate propionate Cellulose acetate butyrate Cellulose acetate propionate nitrate Cellulose acetate butyrate nitrate Cellulose acetate stearate v'Cellulose acetate laurate.

The following are given as illustrations of vari- 'fous-embodiments of my'invention, showing-the Wide adaptability of my colloidizing process.`

:100 parts'of cellulose acetate stearate of about run onto rolls in aA heated atmosphere toeva'poratesthe4 solvent, as is well known.jAl transparent film .or-v sheet was thus formedwhich-exhibited marked flexibility. Y i '1 A 100 parts of a cellulose acetate nitrate, asfor ,example .that disclosed yin'Example I vof Staud such as for example that disclosed: in'Example 'I fof Clarke and Malm application No. 520,149, was dissolved in about 600 parts of ethylene chloride together with 30 parts triphenyll phosphatefand non-hazy coating suitable for lm or sheeting,

and possessing unusual llatness and flexibility.

100 parts of a cellulose acetate-butyrate, such as disclosed in ExampleII of Clarke fand Malm application No. 520,149, was dissolvedin about 1000 parts of methylene chloride. About 40 parts of tricresyl phosphate was added. The solution was roll coated, and the` resultingproduct was found to be a clear and pliable sheeting, Asuitable for wrapping or other purposes for which thin sheeting (for instance of about .001 in. thickness) is desirable.

My invention is also applicable tor thehigher simple esters of cellulose, such as cellulose propionate, cellulose butyrate, cellulose laureate etc.,

by which products of value are produced.r For example a cellulose propionate may be dissolved in ethylene chloride and run onto rolls in a warm environment, to leave a clear sheet suitable for photographic lms, wrapping purposes, laminating glass etc.

My invention is especially applicable in the finer arts, such as the manufacture of photographic lm, Where vno allowance can be made for defects of any kind in the resulting product.`

However, numerous other uses of my invention will at once suggest themselves to one skilled in the art. My invention may be utilized in the making of containers for food or other materials,

which underordinary conditions give off or abV sorb moisture. It can also be employed in the manufacture. of sheets for wrapping or mimeograph and stencil Work, reinforcing of other materials especially those in layer form such as glass, wood, sheet metal, leather etc., covering of surfaces either with a colored or colorless layer, overcoating of thin sheeting, for instance to protect it from moisture, making of artificial leather, articial silk manufacture, and plastics. The employment of colloidized mixed esters, in various capacities, is described in more detail in Clarke and Malm applications Nos. 520,151`and 528,966. y

Some mixed esters, such as may be suitable in my invention, are disclosed for example in Clarke and Malm Patents Nos. 1,704,282 and 1,800,860 and Stand and Waring applications 505,958, 505,959 and 505,960. Mixed esters are Well known in the art at the present time, and any of these which are compatible are Within the contemplation of the present invention. l

What I claim and desire lto secure by Letters Patent of the. United States is:

1. A composition of matter comprising a mixed fatty acid ester of cellulose dissolved in a solvent consisting of `an alkylene chloride selected from the group consisting of ethylene chloride and propylene chloride as the dissolving element for the mixed ester.

2. A composition of matter comprising a mixed fatty acid ester of cellulose dissolved in a solventconsisting of ethylene chloride as the dissolving element for the mixed ester.

3. A composition of matter comprising a mixed fatty acid ester of cellulose dissolved in a solvent consisting of propylene chloride as the dissolving element-for the mixed ester.

4. A composition of matter comprising a cellulose `acetate propionate dissolved in a solvent consistingA of ethylene chloride as the dissolving element for the cellulose acetate propionate.

v5. A composition of matter comprising a cellulose acetate propionate dissolved in a solvent consisting of propylene chloride as the dissolving element for the cellulose acetate propionate.

`6. A composition of matter comprising a cellulose acetate butyrate dissolved in a solvent consisting of ethylene chloride as the dissolving element for the cellulose. acetate butyrate.

7. A composition of matter comprising a cel-` lulose acetate butyrate dissolved in a solvent consisting of propylene chloride as the dissolving element for thecellulose acetate butyrate.,

8. A composition of matter comprising a cellulose ester selected from the group consisting of cellulose acetate propionate and cellulose acetate butyrate, ywhich has a contentvof atleast 15% of acyl groups of 3 to 4 carbon atoms, dissolved in a solvent selected from the `group consistingchloride as the dissolving element for the cellulose ester.

10. A composition of matter comprising ra partially hydrolyzed cellulose acetate-butyrate, dissolved in a solvent consisting of propylene chloride as the dissolving element for the cellulose acetatebutyrate.

11. The process of colloidizing a mixed fatty acid ester of cellulose which comprises dissolving itin a solvent selected from the group consisting of ethylene chloride and propylene chloride as the dissolving element for the ester and then removing the. solvent by evaporation.

CARL J. MALM. 

